In recent years people have used mobile devices to ascertain their current location. Location determination of a device may be useful in various scenarios. For example, it may be useful to ascertain device location when using map applications for navigation. Further examples include accessing location-based services, for instance tailored information regarding yellow-pages services or carrying out searches contextualised to the current device location. Increasingly nowadays, location services have become useful for social networking.
Satellite navigation systems such as the Global Positioning System (GPS) or GLONASS (Globalnaya navigatsionnaya sputnikovaya sistema) are useful for tracking a device's position. However, these systems may be rather unreliable in indoor environments.